1. Field of the Invention
The present invention relates to an image pickup apparatus that generates a three-dimensional image.
2. Description of the Related Art
Recently, an image pickup element that includes a pixel unit cell configured by arranging a plurality of pixels for one microlens (a composite pixel structure) and that outputs a first image signal and a second image signal separated for each pixel of the pixel unit cell is proposed.
Japanese Patent No. 4027113 discloses a configuration in which a part of an image pickup element has a composite pixel structure and this composite pixel is used as a pixel for obtaining information (ranging). However, considering the performance of obtaining the information (ranging performance), it is effective that an entire region of the image pickup element is the composite pixel structure. Therefore, it is proposed that the composite pixel structure is adopted for an entire surface of the image pickup element and that a pixel unit in the composite pixel structure is used for both shooting an image and obtaining the information (for the ranging).
Furthermore, recently, two images (a left-sided image and a right-sided image) having a parallax can be obtained using the pixel having the composite pixel structure. Therefore, achieving a monocular three-dimensional image pickup apparatus in which it is not necessary to use binocular image pickup apparatus (a plurality of image pickup apparatuses) is considered.
When the binocular image pickup apparatus (the plurality of image pickup apparatuses) are used, a three-dimensional effect is determined by a congestion angle of two image pickup apparatuses (cameras), and therefore a stable three-dimensional effect can be obtained even when an aperture stop of an image pickup optical system is changed.
However, when the three-dimensional image is obtained by using the monocular image pickup apparatus, an image shift amount generated on an imaging plane changes in accordance with the aperture stop (a diameter of the aperture stop) of the image pickup optical system. In other words, even when an identical object is shot, the image shift amount is changed by changing the aperture stop and therefore the three-dimensional effect is changed.